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Specialist police teams searched 14 properties in the city on Monday

Six men arrested in Birmingham as part of a large anti-terrorism operation remain in police custody as further searches of properties are carried out.

The men, aged between 25 and 32, are being held on suspicion of the commission, preparation or instigation of an act of terrorism in the UK.

Police raided 14 properties on Monday and remain at 10 of those premises.

A woman held on suspicion of failing to disclose information contrary to the Terrorism Act 2000 has been bailed.

The arrests are thought to be the most significant this year, BBC home affairs correspondent Danny Shaw said.

It is understood the investigation, which has involved security service MI5, relates to suspected Islamist extremism. However, it is not thought that an attack or threat was imminent.

Computer equipment

The men were taken into custody by unarmed officers in the Moseley, Sparkbrook, Sparkhill, Ward End and Balsall Heath areas of Birmingham between 11:30 BST on Sunday and 01:00 on Monday, police said. All those detained are from the Birmingham area.

On Monday specialist teams searched their homes along with seven other properties in the city - six domestic and one commercial. Computer equipment was removed and is being examined.

Investigations are continuing at 10 of those premises, a West Midlands Police spokesman said.

The men are being questioned at an unnamed police station and can be held for up to 14 days.

The seventh person, a 22-year-old woman, from Saltley, Birmingham, was released on bail late on Monday.

West Midlands Police said the "large-scale operation" had been running for some time and had been subject to regular review, adding that the action was necessary "in order to ensure public safety".

The arrests were not related to the Liberal Democrats' conference, which is taking place at the city's International Convention Centre, police said.